<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>左右不动，中间动</title>
    <!-- 重点使用display：flex  自定义部分flex：1-->
    <style>
        .lrstop {
            display: flex;
            height: 800px;
            background-color: rgb(230, 176, 185);
        }
        .lrstop_left {
            width: 200px;
            height: 100%;
            background-color: rgb(129, 125, 173);
        }
        .lrstop_right {
            width: 200px;
            height: 100%;
            background-color:rgb(73, 73, 197);
        }
        .lrstop_conter {
            flex: 1;
            height: 100%;
            background-color: rgb(18, 4, 144);
        }
    </style>
</head>
<body>
    <div class="lrstop">
        <div class="lrstop_left"></div>
        <div class="lrstop_conter"></div>
        <div class="lrstop_right"></div>
    </div>
</body>
</html>